A conventional signal transmission loop consisting of two parallel cables may be used for signal communication purpose. However, the two parallel cables may not counteract the induced voltage when subjected to external magnetic field, or may not counteract the magnetic flux when passing current through the two cables, thereby unable to reduce radio frequency interferences to a communication system and thereby allowing the radio frequency interferences to damage the communication system or some electronic equipments located in the surroundings.
A twisted pair by continuously twisting two cables may be provided for a communication loop for counteracting the induced voltage when subjected to magnetic flux or for counteracting the magnetic flux when passing current through the two twisted cables of the loop in order for reducing radio frequency interefernces.
A conventional printed circuit board may also be provided with parallel signal transmission conductive strips on a single-sided printed circuit board (PCB) or a two-side PCB for signal transmission use, thereby being still unable to exclude the damage or influence caused by radio frequency interferences especially of higher frequency. Since a conventional printed circuit board is formed as a plate-like laminate sheet, not linear cables or wires, the whole PCB sheet can not be twisted to become a "twisted pair" as aforementioned for counteracting the flux or induced voltage for reducing the radio frequency interferences.